Stent grip and systems for use therewith

ABSTRACT

A method and apparatus for reducing the longitudinal aspect of the catheter to stent force having at least one grip member for use with a stent delivery system. The grip engages a stent in the unexpanded state prior to delivery of the stent. The stent may be deployed by retracting a stent retaining sheath. The grip has a body region having an outer diameter, a first end and a second end. The outer diameter of the first end is greater than the outer diameter of the second end. The grip is at least partially constructed from a polymeric material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/611,551, filed Jun. 30, 2003 and issued as U.S. Pat. No. 7,470,282 onDec. 30, 2008, all of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a grip member for use withstent delivery systems and to systems employing one or more of suchgrips.

DESCRIPTION OF RELATED ART

The use of stents, and other implantable medical devices such as grafts,stent-grafts, vena cava filters, etc, hereinafter referred tocumulatively as stents, to maintain the patency of bodily lumens is wellknown.

Stents are typically delivered via a catheter in an unexpandedconfiguration to a desired bodily location. Once at the desired bodilylocation, the stent is expanded and implanted in the bodily lumen.

Typically, a stent will have an unexpanded (closed) diameter forplacement and an expanded (opened) diameter after placement in thevessel or the duct. Some stents are self expanding; some stents areexpanded mechanically with radial outward force from within the stent,as by inflation of a balloon; and some stents, known as hybrid stents,have one or more characteristics common to both self-expanding andmechanically expandable stents.

An example of a mechanically expandable stent and associated deliverysystem is shown in U.S. Pat. No. 4,733,665 to Palmaz, which issued Mar.29, 1988, and discloses a number of stent configurations forimplantation with the aid of a catheter. The catheter includes anarrangement wherein a balloon inside the stent is inflated to expand thestent by plastically deforming it, after positioning it within a bloodvessel.

A type of self-expanding stent is described in U.S. Pat. No. 4,503,569to Dorter which issued Mar. 12, 1985, and discloses a shape memory stentwhich expands to an implanted configuration with a change intemperature. Self-expanding stents are constructed from a wide varietyof materials including nitinol, spring steel, shape-memory memorypolymers, etc.

In many stent delivery systems, particularly those used to deliver aself-expanding stent, the stent is typically retained on the cathetervia a retention device such as a sheath.

The stent may be deployed by retracting the sheath from over the stent.However it is known that in many cases when a sheath is withdrawn from astent, particularly a self-expanding stent constructed of shape memorymaterial, the individual struts or stent members of the stent will pushoutward as they expand back to their “remembered” shape. Often times,but undesirably, as the sheath is withdrawn from about the stent, thestent will tend to migrate longitudinally relative to the stent mountingregion of the catheter. This migration is believed to be caused by alongitudinal component of the force that the stent delivery systemexerts on the stent during withdrawal of the sheath. The tendency of thestent to migrate during sheath retraction may result in the imprecisedelivery of the stent and/or distortion of the stent body.

It would thus be desirable to reduce the longitudinal component of thedelivery system to stent force and/or provide a device for use in astent delivery system that reduces or prevents stent migration duringwithdrawal of the stent retaining sheath. All US patents andapplications and all other published documents mentioned anywhere inthis application are incorporated herein by reference in their entirety.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

A brief abstract of the technical disclosure in the specification isprovided as well only for the purposes of complying with 37 C.F.R. 1.72.The abstract is not intended to be used for interpreting the scope ofthe claims.

BRIEF SUMMARY OF THE INVENTION

This invention may be embodied in a variety of forms. For example, in atleast one embodiment, the invention is directed to a stent deliverysystem that reduces or eliminates the longitudinal component of thesystem to stent force, which may influence or cause migration of thestent or one or more components thereof relative to the catheter duringwithdrawal of the retaining sheath. In some embodiments the reduction inthe longitudinal component of the system to stent force is accomplishedby reducing or minimizing the potential space between the inner cathetershaft or member, upon which the stent is mounted prior to delivery, andthe retractable outer sheath which overlays the stent prior to delivery.

In some embodiments the potential space between the sheath and innermember/stent is reduced by providing a stent delivery system with one ormore stent grips or grip members which underlie at least a portion of astent prior to delivery. A stent grip comprises an annular ring mountedto the catheter shaft. In some embodiments the stent grip has an endportion and a body portion, in the reduced or pre-delivery state thestent is disposed about the body portion and an end of the stent abutsthe end portion of the stent grip.

In at least one embodiment the stent grip comprises a body portionhaving a tapered or varying diameter. In at least one embodiment thediameter of the body tapers from a first diameter at a first end of thebody to a second smaller diameter at a second end of the body. In someembodiment a stent delivery system includes a single tapered grip or apair of tapered grips wherein each grip is respectively positioned onthe catheter shaft to underlie an end of the stent.

In at least one embodiment a stent delivery system comprises a singlestent grip, wherein the single grip has a body which has a lengthsubstantially the same as that of the stent. In some embodiments,multiple grips have body portions that have a combined length that issubstantially less than or equal to that of the stent.

In some embodiments the invention is directed to a stent grip member foruse in a stent delivery system wherein the stent grip is at leastpartially constructed of a polymer material. In some embodiments thematerial is preferably of a fairly soft durometer value to allow a stentto be effectively gripped or at least partially imbedded within thematerial of the grip.

In some embodiments a grip is insert molded, molded and then bonded tothe catheter shaft, or otherwise formed separately or in conjunctionwith the catheter shaft or portion thereof.

These and other embodiments which characterize the invention are pointedout with particularity in the claims annexed hereto and forming a parthereof However, for a better understanding of the invention, itsadvantages and objectives obtained by its use, reference should be madeto the drawings which form a further part hereof and the accompanyingdescriptive matter, in which there is illustrated and described aembodiments of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(s)

A detailed description of the invention is hereafter described withspecific reference being made to the drawings.

FIG. 1 is a perspective view of an embodiment of the invention.

FIG. 2 is a cross-sectional side view of an embodiment of the invention.

FIG. 3 is a cross-sectional side view of an embodiment of the invention.

FIG. 4 is a cross-sectional side view of an embodiment of the invention.

FIG. 5 is a cross-sectional side view of an embodiment of the invention.

FIGS. 6 and 7 are close up cross-sectional side views of an embodimentof the invention shown during a stent delivery process.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific preferred embodiments of theinvention. This description is an exemplification of the principles ofthe invention and is not intended to limit the invention to theparticular embodiments illustrated.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated.

As mentioned above the present invention is embodied in a variety offorms. For example, in the embodiment shown in FIG. 1 the invention isembodied in a stent retaining member or grip, indicated generally at 10,which has an outer diameter that tapers from a first, larger diameter ata first end 12 of the grip 10 to a second, smaller diameter at a secondend 14 of the grip.

In some embodiments, an example of which is shown in FIG. 2, the grip 10includes a hub or dam 16 adjacent to the first end 12. At least aportion of the hub 16 has a diameter larger than the diameter of thegrip body 18. In at least one embodiment such as is shown in FIG. 3 astent 20 or other implantable medical device may be positioned adjacentto or butted up against an inner surface 22 of the hub 16 when the stentis disposed about the grip body 18 prior to expansion of the stent.

As is illustrated in FIG. 4, in some embodiments, a stent deliverycatheter, indicated generally at 100, comprises one or more grips 10.One or more grips 10 are engaged or incorporated onto the inner shaft ormember 30 of the catheter 100. The position of the grips 10 on the innermember 30 substantially correspond to the area of the member whichdefines a stent mounting region 32. A stent 20 is disposed about thestent mounting region 32 and in the reduced or pre-delivery state isengaged to at least a portion of each grip 10.

Where a single grip 10 is utilized, such as is shown in FIG. 5 the body18 of the grip underlies at least a portion of the stent. In at leastone embodiment, the body 18 of the grip 10 has a length which is atleast as long as that of the stent 20.

Where multiple grips are used such as in FIG. 4, the lengths of eachgrip body 18 are approximately half the length of the stent 20 or less.In at least one embodiment the diameter of the grips taper from a largerdiameter at the ends 34 of the stent 20 to a smaller diameter under thebody 36 of the stent 20.

In some embodiments of the invention stent 20 is a self-expandabledevice such as are known. Stent 20 may be at least partially constructedfrom nickel, titanium, stainless steel, other metals and alloys thereof,such as nitinol. Other materials suitable for use in constructing stent20 may include shape memory polymers, etc.

In the various embodiments of the invention, the grip 10 effectivelyreduces the longitudinal aspect of the catheter to stent force byensuring that the individual struts 40 of the stent 20 are at ashallower or smaller angle upon exiting the confines of a sheath, sleeveor other stent retaining device 42 when the sheath 42 is retracted toallow the stent 20 to expand such as is shown in FIGS. 6 and 7.

In some embodiments, a grip 10 is at least partially constructed of apolymer material. In some embodiments the material has a Shore-Adurometer value of about 60 to about 90 and in some embodiments about 70to about 90. In some embodiments the grip is at least partiallyconstructed from one or more materials such as: polyether ester; HYTREL(polyether-ester copolymer) by Du Pont Co.; polyether block amides;ARMTEL (polyether-ester copolymer) by DSM Engineering Plastics;PELLETHANE (polyurethane with polyester, polyether, or polycaprolactonecopolymers) by Dow Chemical; polyurethane; aromatic polyether basedpolyurethanes, such as TECOTHANE available from Thermedics Inc.;silicon, rubber, or foam, etc.

In at least one embodiment the grip 10 is at least partially constructedfrom a radiopaque polymer or other radiopaque material.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

1. A stent delivery device, comprising: an elongate shaft; a first gripmember disposed on the shaft, the first grip member including a firsthub, a first proximal portion adjacent and distal to the first hub, anda first distal portion; wherein the first hub has a first hub outerdiameter, wherein the first proximal portion has a first proximal outerdiameter less than the first hub outer diameter, and wherein the firstdistal portion has a first distal outer diameter less than the firstproximal outer diameter; a stent disposed over the first proximalportion and the first distal portion of the first grip member; whereinthe stent is butted against the first hub; a tubular sheath disposedover the stent; and a second grip member disposed on the shaft andpositioned distally of the first grip member, wherein the second gripmember includes a second hub and a second proximal portion, and whereinthe second hub has a second hub outer diameter, and wherein the secondproximal portion has a second proximal outer diameter less than thesecond hub outer diameter.
 2. The stent delivery device of claim 1,wherein the stent is disposed on at least a portion of the second gripmember.
 3. The stent delivery device of claim 1, wherein a gap is formedbetween the first grip member and the second grip member, and wherein atleast a portion of the stent is disposed along the gap.
 4. The stentdelivery device of claim 1, wherein the first grip member includes apolymer.
 5. The stent delivery device of claim 1, wherein the first gripmember includes a radiopaque material.
 6. A stent delivery device,comprising: an inner member; a first grip disposed on the inner member,the first grip including a first hub and a first tapered body extendingdistally from the first hub; a stent disposed over at least a portion ofthe first grip; wherein the stent is butted against the first hub; atubular sheath disposed over the stent; and a second grip disposed onthe inner member and positioned distally of the first grip, the secondgrip including a second hub and a second tapered body extending from thesecond hub, the second tapered body having an outer diameter that isless than an outer diameter of the second hub; and wherein the stent isdisposed on at least a portion of the second grip.
 7. A stent deliverydevice, comprising: an inner member; a first grip disposed on the innermember, the first grip including a first hub and a first tapered bodyextending distally from the first hub; a stent disposed over at least aportion of the first grip; wherein the stent is butted against the firsthub; a tubular sheath disposed over the stent; and a second gripdisposed on the inner member and positioned distally of the first grip,the second grip including a second hub and a second tapered bodyextending from the second hub, the second tapered body having an outerdiameter that is less than an outer diameter of the second hub; andwherein a gap is formed between the first grip and the second grip, andwherein at least a portion of the stent is disposed along the gap.